DESCRIPTION: The objective of this study is to determine the relationship between body position and cerebral dynamics, hemodynamics, and systemic oxygenation in patients with traumatic brain injury (TBI). Trauma research suggests that positioning may be related to multi- system consequences including altered hemodynamics, impaired gas exchange, changes in cerebral tissue perfusion, and increases in intracranial pressure. Neuroscience research concludes that achievement of multi-system stability is associated with prevention of TBI-related secondary cerebral injury which results from intracranial hypertension, systemic hypotension, and hypoxia. Research questions addressed in this study include: Are there statistically and/or clinically significant differences in cerebral dynamics, hemodynamics, and systemic oxygenation measurements among patients with TBI related to assumption of various body positions? The independent variable of body position includes nine variations of backrest, left lateral, and right lateral positions, each with 0, 15 and 30 degrees of head elevation. Biomedical instrumentation will be used to measure the dependent variables of cerebral dynamics, hemodynamics, and systemic oxygenation. Injury Severity SCores, (ISS) and Apache III Scores are treated as covariates in this study. A minimum sample size of 40 patients is required to provide adequate statistical power for this quasi-experimental, within-subject control, repeated measures study design using analysis of Covariance (ANCOVA) (f=0.25, a=0.007, u=8, 1- B=0.80). Results of this study will determine best practice(s) for positioning TBI patients with respect to optimization of multi-systemic parameters. Subsequent intervention investigating the clinical application of these research-based positioning practices are expected to demonstrate improved physiological, functional, cognitive, perceptual (i.e., quality of life, and financial outcomes of TBI patients by reducing the incidence of secondary cerebral injury and secondary disabilities (Healthy People 2000)